1. Field of the Invention
The present invention relates to a magneto-generator that is driven by an internal combustion engine, for example.
2. Description of the Related Art
A magneto-motor that is used in a closed compressor is disclosed in JP-A-2001-28870. A technique of reducing ineffective, short-circuited magnetic flux by forming, with a resin as a non-magnetic material, top and bottom end plates of an iron core that is a lamination of magnetic steel plates is described in paragraph 0024 of this reference. Whereas a technique of using magnetic steel plates as the end plates is known, the magnetic loss occurring in the end plates can be reduced by forming the end plates with a resin as a non-magnetic material.
In magneto-generators in general driven by an internal combustion engine, a recent trend is such that the number of magnetic poles is increased to increase the frequency of the output voltage, make its rectified voltage flatter, and increase the output current. In this case, the magnetic loss of the stator core tends to increase with the frequency. It is therefore necessary to minimize the magnetic loss in the end plates.
To reduce the magnetic loss in the end plates, it is important that the end plates be made of a non-magnetic material. Since the generation coils are wound on the teeth of the stator core including the end plates, the end plates should be rigid enough to hold the generation coils in a prescribed shape and should be configured effectively so as to provide sufficient insulation between the stator core and the generation coils.
Among the above requirements, the insulation that is necessary between the stator core and the generation coils can be attained easily by forming the end plates with a resin as in the above prior art technique. In contrast, it is difficult to impart sufficient rigidity to the end plates. One method for imparting sufficient rigidity to the end plates made of a resin is to insert-mold resin plates in such a manner that it incorporates the stator core therein. However, this requires a special insert-molding step. Further, parts of the end plates that are required to be particularly rigid should be thick, which restricts the winding spaces.